1. Field of the Invention
The present invention relates to a data input/output apparatus for the input/output of data with a sequence controller and a control apparatus of a die casting machine using the same.
2. Description of the Related Art
A sequence controller sequentially controls an external apparatus according to a sequence program prepared in advance. This sequence controller is provided with an input/output unit for transferring signals with the external apparatus.
The input/output unit is provided with a predetermined number of terminals. For example, input terminals are electrically connected to input apparatuses such as switches, while output terminals are electrically connected to output apparatuses such as lamps or light emitting diodes (LED).
The sequence controller processes data comprised of level signals input from the input apparatus by a processor built in the sequence controller or outputs the data processed at the processor as level signals to the output apparatus.
Also, the sequence controller is used as a control apparatus of an automatically controlled machine, for example, a die casting machine or an numerical controlled machine tool. Data is input and output with the sequence controller as the control apparatus by a control panel provided with switches and lamps.
The above sequence controller, however, is limited in the number of the input/output terminals of the input/output unit.
For this reason, when the number of the input apparatuses and/or output apparatuses to be connected is larger than the number of the input/output terminals of the input/output unit, usually extension input/output units are added to the sequence controller.
For example, as shown in FIG. 1, a sequence controller 101 is provided with a processor 102, a program memory 103, and an input/output unit 104. These processor 102, program memory 103, and input/output unit 104 are connected by buses.
The extension input/output units 105 and 106 are mounted in for example slots provided in the sequence controller 101 and directly connected to the buses.
A control panel 130 is provided with switches SW and lamps RP. These switches SW and lamps RP are electrically connected to input/output terminals 104a, 105a, and 106a of the input/output unit 104 and extension input/output units 105 and 106 by wires 120, 121, and 122.
When the sequence controller 101 and the control panel 130 are connected by using the extension input/output units 105 and 106 as described above, the amount of wires becomes three times the case where only the input/output unit 104 is connected to the control panel 130.
Also, when the switches SW and the lamps RP are increased, the number of the wires is increased accordingly. When the wires are increased, there are the disadvantages that a large space is taken up by the wires, the apparatus becomes large, and the cost rises.
Particularly, in a die casting machine, it is necessary to control the injection to fill a molten metal into the cavity of the die, control clamping for clamping the dies, and control apparatuses attached to the die casting machine such as a spray apparatus, conveyance apparatus, etc. In order to control these according to predetermined procedures, large number of various sensors are necessary. It is necessary to input detection signals of these sensors to the sequence controller or output them through the sequence controller to the control panel.
Accordingly, in a die casting machine as well, the number of the input/output signals of the sequence controller is very large, so the number of wires between the sequence controller 101 and the control panel 130 is increased.
In a die casting machine, molten metal is used. Therefore, the molten metal is scattered around the die casting machine creating a bad environment. For example, when the molten metal adhers to the wires for connecting the sequence controller and the control panel, there is a possibility of the wires breaking or of wires short-circuiting with each other. For this reason, the number of the wires for connecting the sequence controller and the control panel is preferably as small as possible.
An object of the present invention is to provide a data input/output apparatus capable of decreasing the number of wires with the sequence controller and not requiring a change of the number of the wires even if the number of the input/output points of the data is increased.
Another object of the present invention is to provide a control apparatus of a die casting machine with a decreased number of wires between the sequence controller and the control panel.
According to a first aspect of the present invention, there is provided A data input/output apparatus for the input/output of data with respect to a sequence controller provided with an input/output unit having a predetermined number of terminals for the input/output of data and a processing means for transferring data with the input/output unit and processing data, comprising a plurality of external input/output means for sending data to the sequence controller or receiving data from the sequence controller; a plurality of connecting wires electrically connected to buses for the transmission of data between the input/output unit and the processing means; a plurality of electronic switches electrically connected to the external input/output means, electrically and commonly connected to the connecting wires, and outputting signals responsive to levels of input signals to the external input/output means or the connecting wires in accordance with input of a selection signal; a selecting means electrically connected to the connecting wires and outputting the selection signal to the electronic switch connected to the external input/output means being selected by the processing means.
According to a second aspect of the present invention, there is provided a control apparatus for sequence control of a die casting machine for filling a molten metal in a die cavity and casting a product, comprising a machine controller for controlling the die casting machine; a sequence controller provided with an input/output unit having a predetermined number of terminals for the input/output of data and a processing means for transferring data with the input/output unit and processing data and processing the data and instructing the machine controller according to a sequence program predetermining procedures to be performed by the die casting machine; a plurality of connecting wires electrically connected to buses for the transmission of data between the input/output unit and the processing means; a plurality of external input/output means for sending data defining the operation of the die casting machine to the machine controller to the sequence controller or receiving data defining an operating state of the die casting machine from the sequence controller; a plurality of connecting wires electrically connected to the buses for the transmission of data between the input/output unit and the processing means; a plurality of electronic switches electrically connected to the external input/output means, electrically and commonly connected to the connecting wires, and outputting signals responsive to levels of input signals to the external input/output means or the connecting wires in accordance with input of a selection signal; a selecting means electrically connected to the connecting wires and outputting the selection signal to the electronic switch connected to the external input/output means being selected by the processing means.
In the present invention, when data is output from the sequence controller, the data is input through the buses and the connecting wires to the electronic switches.
Among the plurality of electronic switches, electronic switches selected by the processing means of the sequence controller output signals responsive to signal levels of the data input through the buses and the connecting wires to the external input/output means (control panel).
On the other hand, among the data input from the external input/output means, the data input to the electronic switches selected by the processing means output signals responsive to signal levels of the input data to the processing means of the sequence controller via the connecting wires and the buses.
In this way, in the present invention, the transfer of data between the sequence controller and the external input/output means is handled not through the input/output terminals of the input/output unit, but through the buses of the sequence controller. The data input from the external input/output means and the data output to the external input/output means are, however, handled in the same way as the data input to and output from the input/output terminals of the sequence controller.
Also, since a plurality of electronic switches are commonly connected to a limited number of wires, even if the number of the data input/output points of the external input/output means is increased, the number of the connecting wires connected to the buses will not be increased. Further, even when it is desired to increase the number of the data input/output points of the external input/output means, the number of the electronic switches may be increased. It is not necessary to increase the number of the connecting wires connected to the buses.